The GENC Standard specifies a profile of ISO 3166, Codes for the
representation of names of countries and their subdivisions. This
profile addresses unique U.S. Government requirements for: restrictions
in recognition of the national sovereignty of a country; identification
and recognition of geopolitical entities not included in ISO 3166; and
use of names of countries and country subdivisions that have been
approved by the U.S. Board on Geographic
Names (BGN).

The US Government cannot use ISO 3166 directly. US Public Law
80-242 (1947) requires the US Government to use geographic names
that have been approved by the BGN. ISO 3166 contains some country and
subdivision names that vary from those approved by the BGN. The
geopolitical entities included in ISO 3166 are those that are
recognized by the United Nations (UN). The GENC Ed1.0 is the US
Government implementation of ISO 3166-1 that conforms to BGN and US
Government recognition policy.

For reasons cited above,
ISO 3166-1:2006 has been withdrawn upon FGDC endorsement of the
GENC Standard Edition 1.0.

The Country Codes Working Group of the Geospatial Intelligence Standards
Working Group (GWG) developed the GENC Ed1.0. It referred
the GENC Ed1.0 to the FGDC Standards Working Group for
recommendation for FGDC endorsement. The FGDC Coordination Group
subsequently approved the GENC Ed1.0 for FGDC endorsement, and the FGDC
Steering Committee took the final action to endorse the standard.